Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

European Conference on Optical Communication

Field Demonstration of Quantum Key Distribution Coexisting with 110-Tb/s Classical Transmission over Multi-Core Fibers

Qi Wu, Domenico Ribezzo, Giammarco Di Sciullo, S. Cocchi, Divya Ann Shaji, Lucas Zischler, Ruben Soares Luis, Paolo Serena, Chiara Lasagni, A. Bononi, Tetsuya Hayashi, A. Gagliano, P. Martelli, Alberto Gatto, Paola Parolari, Pierpaolo Boffi, Davide Bacco, Alessandro Zavatta, Yixiao Zhu, Weisheng Hu, Zenglin Xu, Mark Shtaif, Andrea Marotta, Fabio Graziosi, Antonio Mecozzi, Cristian Antonelli

Published Sep 28, 2025• 2 citations
Publisher

Abstract

We report, for the first time, a field demonstration of quantum key distribution coexisting with 110- Tb/s full C-band dense wavelength-division multiplexed coherent transmission over field-deployed uncou-pled-core multi-core fibers with a standard 125-µm cladding diameter in L'Aquila, Italy. Various coexistence configurations and transmission distances are evaluated.

DOI
10.1109/ecoc66593.2025.11263014

Related papers

Coexisting QKD and Real-Time Encrypted High-Speed Fiber-Optic Communication in Field-Deployed Multi-Core Fibers

Ibrahim Mohamed Ramadan, Giammarco Di Sciullo, Qi Wu +18 more

Quantum key distribution (QKD) coexisting with ultra-high-capacity classical optical signals over the same fiber is widely regarded as a cornerstone of future quantum-safe networks. This approach eliminates the need for dedicated fibers for QKD, significantly reducing infrastructure costs and facilitating large-scale deployment. As a promising foundation for next-generation high-capacity optical networks, multi-core fiber (MCF) opens new possibilities for such coexistence, offering an elegant and spectrum-efficient solution for the integration of quantum and classical channels. Here, we report the first field trial of QKD securely coexisting with bidirectional 106.7 Tb/s full-C-band dense wavelength-division-multiplexed coherent classical transmission over 25.2 km of installed standard-cladding diameter (125 μm) uncoupled-core four-core fiber in L'Aquila, Italy. Despite a classical launch power of 20 dBm per core, a secure key rate of 1.7 kb/s was achieved, using a commercial QKD system. We used the secure keys to achieve real-time encryption of up to 132 Gb/s live traffic within a 400 Gb/s channel, with key refresh intervals as short as 15 seconds. We used hardware encryption, introducing only 52 μs end-to-end latency and jitter below 4 μs compared to the unencrypted case. These results represent a major milestone toward practical, secure, and scalable integration of quantum and classical communication over deployed metropolitan multi-core fiber infrastructure.

Journal of Lightwave Technology•Jun 16, 2026•0 citations

Demonstration of a Cross-Encoded RFI QKD system in a field-deployed multi-core fiber

Massimo Giacomin, Julian Morales Traktenberg, Matías Rubén Bolaños +6 more

This work showcases the robustness of a novel Reference-Frame-Independent Quantum Key Distribution apparatus integrated in an uncoupled-core 8-core fiber deployed in L’Aquila, Italy, coexisting with classical traffic in adjacent cores within the same telecom band.

Optical Fiber Communication Conference•Jan 1, 2026•0 citations

Integration of quantum key distribution and high-throughput classical communications in field-deployed multi-core fibers

Qi Wu, Domenico Ribezzo, Giammarco Di Sciullo +23 more

Quantum key distribution (QKD) is a secure communication method for sharing symmetric cryptographic keys based on the principles of quantum physics. Its integration into the fiber-optic network infrastructure is important for ensuring privacy in optical communications. Multi-core fibers (MCFs), the likely building blocks of future high-capacity optical networks, offer new opportunities for such integration. Here, we experimentally demonstrate, for the first time, the coexistence of discrete-variable QKD and high-throughput classical communication in the C-band over a field-deployed MCF with industry standard cladding diameter of 125 μm. Specifically, we demonstrate successful secure-key establishment in one core of a 25.2-km uncoupled-core MCF, while simultaneously loading the remaining three cores with full C-band counter-propagating classical traffic at an aggregate net rate of 110.8 Tb/s. By proposing and experimentally validating an improved analytical model for inter-core spontaneous Raman scattering noise, we find that this configuration is optimal for our deployed MCF link as it is immune to four-wave mixing, that becomes relevant when the quantum and classical signals are propagating in the same direction. Our findings make an important step forward in demonstrating the integration of QKD and classical transmission in uncoupled-core multi-core fibers for next-generation optical communication networks.

Light Science & Applications•Aug 13, 2025•31 citations

Demonstration of a three-node wavelength division multiplexed hybrid quantum-classical network through multicore fiber

Joshua Dugre, Samuel Fritsch, R. Krishna Mohan

This paper presents the practical development of a hybrid quantum-classical network through multiple links of four- and seven-core industrial jacketed multicore fiber. The network utilizes dense wavelength division multiplexing to propagate the C-band quantum and classical information in the same core, making full use of the unidirectional nature of quantum key distribution. Total network transmission of 1.16 Tbps is achieved with a total network secret key rate of approximately 7.4 kbps through a combination of 1 and 2 km links of multicore fiber. The deployment configurations presented are independent of the classical modulation format, and the maximal transmission rate for an operational hybrid network is found to be dependent only on classical optical power occupying the quantum channel wavelength. A model was developed to estimate the impact classical optical channels will have on coexisting quantum channels, which may allow engineers to quickly validate hybrid network designs.

Journal of Optical Communications and Networking•Nov 18, 2024•4 citations

Co-Existence of Quantum-Key Distribution and Classical Transmission in Space-Division Multiplexed Fiber-Optic Systems: Modelling and Validation Over Field-Deployed Multi-Core Fibers

Qi Wu, Domenico Ribezzo, Giammarco Di Sciullo +23 more

We propose an analytical model for inter-core spontaneous Raman scattering noise in multi-core fiber systems with co-existing quantum-key distribution and classical transmission in the C-band. The model is experimentally validated over field-deployed multi-core fibers.

European Conference on Optical Communication•Sep 28, 2025•0 citations

Field Trial of 7 × 89λ × 256 Gb/s C-Band Classical / CVQKD Co-Existence Transmission over 7-Core Fiber

Xin Wang, Jintao Wang, Yingyu Chen +5 more

We successfully demonstrated the coexistence of CV-QKD and 89 classical channels separated by 1 nm in C-band transmitted over a 16.7 km field deployed 7-core fiber, achieving 35 Mb/s secure key rate with 22.8 Tb/s classical data per core.

Asia Communications and Photonics Conference•Nov 4, 2023•16 citations
We report, for the first time, a field demonstration of quantum key distribution coexisting with 110- Tb/s full C-band dense wavelength-division multiplexed coherent transmission over field-deployed uncou-pled-core multi-core fibers with a standard 125-µm cladding diameter in L'Aquila, Italy. Various coexistence configurations and transmission distances are evaluated.
Quantum key distribution (QKD) coexisting with ultra-high-capacity classical optical signals over the same fiber is widely regarded as a cornerstone of future quantum-safe networks. This approach eliminates the need for dedicated fibers for QKD, significantly reducing infrastructure costs and facilitating large-scale deployment. As a promising foundation for next-generation high-capacity optical networks, multi-core fiber (MCF) opens new possibilities for such coexistence, offering an elegant and spectrum-efficient solution for the integration of quantum and classical channels. Here, we report the first field trial of QKD securely coexisting with bidirectional 106.7 Tb/s full-C-band dense wavelength-division-multiplexed coherent classical transmission over 25.2 km of installed standard-cladding diameter (125 μm) uncoupled-core four-core fiber in L'Aquila, Italy. Despite a classical launch power of 20 dBm per core, a secure key rate of 1.7 kb/s was achieved, using a commercial QKD system. We used the secure keys to achieve real-time encryption of up to 132 Gb/s live traffic within a 400 Gb/s channel, with key refresh intervals as short as 15 seconds. We used hardware encryption, introducing only 52 μs end-to-end latency and jitter below 4 μs compared to the unencrypted case. These results represent a major milestone toward practical, secure, and scalable integration of quantum and classical communication over deployed metropolitan multi-core fiber infrastructure.
Quantum key distribution (QKD) is a secure communication method for sharing symmetric cryptographic keys based on the principles of quantum physics. Its integration into the fiber-optic network infrastructure is important for ensuring privacy in optical communications. Multi-core fibers (MCFs), the likely building blocks of future high-capacity optical networks, offer new opportunities for such integration. Here, we experimentally demonstrate, for the first time, the coexistence of discrete-variable QKD and high-throughput classical communication in the C-band over a field-deployed MCF with industry standard cladding diameter of 125 μm. Specifically, we demonstrate successful secure-key establishment in one core of a 25.2-km uncoupled-core MCF, while simultaneously loading the remaining three cores with full C-band counter-propagating classical traffic at an aggregate net rate of 110.8 Tb/s. By proposing and experimentally validating an improved analytical model for inter-core spontaneous Raman scattering noise, we find that this configuration is optimal for our deployed MCF link as it is immune to four-wave mixing, that becomes relevant when the quantum and classical signals are propagating in the same direction. Our findings make an important step forward in demonstrating the integration of QKD and classical transmission in uncoupled-core multi-core fibers for next-generation optical communication networks.
This paper presents the practical development of a hybrid quantum-classical network through multiple links of four- and seven-core industrial jacketed multicore fiber. The network utilizes dense wavelength division multiplexing to propagate the C-band quantum and classical information in the same core, making full use of the unidirectional nature of quantum key distribution. Total network transmission of 1.16 Tbps is achieved with a total network secret key rate of approximately 7.4 kbps through a combination of 1 and 2 km links of multicore fiber. The deployment configurations presented are independent of the classical modulation format, and the maximal transmission rate for an operational hybrid network is found to be dependent only on classical optical power occupying the quantum channel wavelength. A model was developed to estimate the impact classical optical channels will have on coexisting quantum channels, which may allow engineers to quickly validate hybrid network designs.